A known apparatus automatically checks potatoes in such a manner that they are sorted according to different criteria, such as size, presence of different types of fungal diseases, damages etc. Unacceptable potatoes can be discarded thereby.
Until now, this procedure has been carried out using an apparatus, where the potatoes have been advanced in longitudinal direction by means of a feeding device in the form of a so-called vibration feeder to an endless belt, i.e. an endless conveyor belt with rotating rollers, the axes of said rollers extending transversely to the advance direction. Each of said rollers is provided with a plurality of circumferential grooves, the number of said grooves corresponding to the number of rows, said grooves being evenly spaced across each roller, seen in the axial direction thereof, and arranged with respect to each other from roller to roller in the advance direction of the conveyor belt in such a manner that they are mutually aligned so that the potatoes can be advanced in rows in the grooves, said potatoes being taken up individually by two adjacent rollers. In general, potatoes have an oblong shape and will therefore arrange themselves with their longitudinal axes extending parallel to the axes of the rollers, while being rotated around the longitudinal axes thereof by the rotation of the rollers. During the continuous movement of the endless belt the potatoes are conveyed to a position underneath a camera taking pictures of each individual potato in a conventionally known manner, said pictures being sent to a conventionally known image processing means recording the condition of the potato in question. At the end of the endless belt, there is a sorting device which may be controlled by the image processing means, if desired, so that here the potatoes are deposited in compartments depending on their condition.
As the potatoes are usually only rotated substantially around the longitudinal axes thereof, the ends of the potatoes have a tendency to remain hidden from the camera arranged above. This applies in particular to the outermost ends of potatoes in the outermost rows on the endless belt. Thus, there is a risk of potatoes that should have been discarded being approved for sale.
The described automatic sorting of potatoes has several advantages compared to manual sorting, as it has been found that using this method, fewer good potatoes are being discarded and fewer potatoes to be discarded are approved. This is due to the fact that manual sorting requires the operator in question to view each individual potato and make a quick judgement, which can be difficult to sustain over a longer period at an acceptable suitable speed.